1. Field of the Invention
The present invention relates to a nucleic acid detection sensor which electrochemically detects whether a target nucleic acid chain in a test liquid has a specific base sequence.
2. Description of the Related Art
Recently, a genetic test technique with a nucleic acid chain fixed array (DNA array) is made attention as a nucleic acid detection sensor (see “Beattie et al. 1993, Fodor et al. 1991, Khrapko et al. 1989, Southern et al. 1994”).
DNA array indicates the array of a glass and a silicon with several cm squares where DNAs with different 101 to 105 kinds of arrays is fixed. The signed test liquid gene is reacted with a fluorescent dye and a radioisotope (RI), etc. on the array, or the unsigned test liquid gene and the compound of the sign oligonucleotide are reacted by the sandwich hybridization. When a complementary array to the DNA on the array exists in the test liquid, the signal (fluorescent intensity and RI intensity) which is derived from the sign by a specific part on the array is obtained. If the arrangement and the position of the fixed DNA are known beforehand, the base sequence which exists in the test liquid gene can be easily checked. Since a lot of information on the base sequence with the small amount sample can be obtained, DNA array is expected very much not only in the gene detection technique and also in the sequence technical (see “Pease et al. 1994, Parinov et al. 1996”).
There are a fluorescent detection method, RI intensity detection method, and an electrochemical detection method, etc. as a technique which detects the nucleic acid which is combined with the nucleic acid detection sensor. A sign of the sample gene and a complex system are not required in an electrochemical technique. Therefore, the miniaturization of the system can be expected. In addition, since the electrode used, the electrochemical technique has an advantage that an electric reactive control can be easily performed.
Especially, among the nucleic acid detection sensors which use an electrochemical technique, the sensor having a DNA array configuration in which a plurality of electrodes where a different probe nucleic acid chain is fixed are arranged in a X-Y matrix is expected as an extremely useful technical which can detect many kinds of nucleic acids with a short time. However, the equal voltage should be applied to a lot of nucleic acid chain fixed electrodes in this sensor. Therefore, this sensor has the problems such as the circuit configuration is complex, and the response speed and accuracy are not sufficient.